Republican Sen. Marco Rubio — one of the bipartisan group of eight Senators proposing an overhaul of the nation's immigration system — managed to make a believer of conservative radio host Rush Limbaugh.

But Limbaugh took a different tone on Tuesday when speaking with Rubio directly.

Limbaugh opened the segment by asking Rubio, "Why are we doing this now?"

"The key is this was going to be an issue," Rubio said. "I thought it was critically important that we outline the key principles." He said he doesn't want the immigration debate to be "defined" by President Barack Obama and Democrats.

Rubio confirmed that he wouldn't support any bill that doesn't attach conditions for border security in exchange for a path to citizenship. Limbaugh said that he thinks Democrats don't want border security because they want more voters to come in that typically vote Democratic.

"I am confident that given a fair chance, I can convince most Americans that limited government and free enterprise is better for them. Because that's the reason that they came here," Rubio said.

Limbaugh said he doesn't see where there's any common ground between Republicans and Obama.

Rubio said that the President has an "important decision."

"I'm not going to be part of a bidding war to see who can come up with the most lenient path forward," Rubio said. He repeats that he won't support a bill without any enforcement "triggers."

Limbaugh then asked Rubio whether he thinks Obama really wants reform or if he keeps wanting to use it as a political wedge issue.

"That's precisely why I thought it was important to get our principles out there early," Rubio said, noting that he didn't want Obama to get out ahead in the debate.

At that point, Rubio appeared to have convinced Limbaugh.

"What you are doing is admirable and noteworthy," Limbaugh tells Rubio. "You are recognizing reality."

Limbaugh closes by asking what result he thinks will happen if this effort fails. Rubio said that it depends "how it fails."

"There's a lot of work to be done here. We're nowhere near the finish line. But it's important to outline our principles," Rubio said.

"Obama won't be president forever. ... We have to write laws with that in mind, as well," he added.

The interview closed with this exchange from Rush: "You've got a tough job ahead of you."

Rubio: "Yeah. ... I pray that it works out. I can't guarantee that it will."

After the segment with Rubio, Limbaugh said of Rubio, "Is that a good guy or what, folks? Here is a guy who does not fear talk radio."